VERITAS Volume Manager 3.5 Administrator's Guide (September 2004)

Administering Cluster Functionality
Upgrading Cluster Functionality
Chapter 10 355
Upgrading Cluster Functionality
The rolling upgrade feature allows you to upgrade the version of VxVM
running in a cluster without shutting down the entire cluster. To install
the new version of VxVM running on a cluster, make one node leave the
cluster, upgrade it, and then join it back into the cluster. This operation
is repeated for each node in the cluster.
Each Volume Manager release starting with Release 3.1 has a cluster
protocol version number associated with it. The cluster protocol version
is not the same as the release number or the disk group version number.
The cluster protocol version is stored in the /etc/vx/volboot file.
During a new installation of VxVM, the vxdctl init command creates
the volboot file and sets the cluster protocol version to the highest
supported version.
Each new Volume Manager release supports two cluster protocol
versions. The lower version number corresponds to a previous Volume
Manager release. This has a fixed set of features and communication
protocols. The higher version number corresponds to the new release of
VxVM which has a new set of these features. If the new release of VxVM
does not have any functional or protocol changes, but only bug fixes or
minor changes, the cluster protocol version remains unchanged. In this
case, the cluster protocol version does not need to be upgraded.
During a rolling upgrade, each node must be shut down and the Volume
Manager release with the latest cluster protocol version must be
installed. All nodes that have the new release of VxVM continue to use
the lower level version. A slave node that has the new cluster protocol
version installed tries to join the cluster. If the new cluster protocol
version is not in use on the master node, it rejects the join and provides
the current cluster protocol version to the slave node. The slave retries
the join with the cluster protocol version provided by the master node. If
the join fails at this point, the cluster protocol version on the master node
is out of range of the protocol versions supported by the joining slave. In
such a situation, you must upgrade the remainder of the cluster through
each intermediate release of VxVM to reach the latest supported cluster
protocol version.